PV Array Fault Diagnosis

Why we need PV array fault diagnosis?

Photovoltaic (PV) systems provide a promising solution to directly utilizing solar energy and are currently gaining in popularity as the technologies are mature and the material costs are driven down. However, current bottlenecks are still associated with high costs and low efficiency of PV systems. In addition to capital costs, the maintenance costs for PV panels are also high because they are generally installed in outdoor environments and they are prone to various mechanical and electrical faults. These faults can result in additional power losses, hotspots, different irradiances between PV modules. In turn, these lead to loss of production and reduced generation efficiency. If left untreated, the faults may propagate to neighbouring modules and cause a complete failure of the PV strings. As a result, the reliability, availability and maintainability (RAM) of PVs have been a heated topic in research and application community over the last three decades.

What are the challenges for PV array fault diagnosis?

The electrical and thermal characteristics of fault PV array;

For small scale PV array, how to design low cost and online fault diagnosis method with optimized voltage sensor locations

How to achieve fault diagnosis for large scale PV array?

How are these challenges being addressed by SISER researchers?

University of Strathclyde power electronics and motor drive (PEMD) group has strong knowledge in PV array fault diagnosis. They investigate the PV array electrical and thermal characteristics under fault condition. They build a parameter based model to linkage the thermal characteristics and electrical characteristics. By this model, the temperature distribution can be illustrated. For small scale PV array, they develop a fault diagnosis strategy, in which string current sensors are removed and the number of voltage sensors is also reduced by optimizing the location of voltage sensors; an online two-section fault diagnosis method is developed to locate faulty PV modules; and the state of health information from this work can be also used for the MPPT and PV array dynamical reconfiguration. For large scale PV array, the thermal camera is employed to diagnostic the fault PV array. The driver behind the IR image degeneration has been studied. Two main factors have been identified to be the cause of this phenomenon, namely the variation of atmospheric transmission and directional emissivity. A temperature recovery method has been proposed to recover the real temperature from the degenerated image.